Seed bed mulches accomplish a number of functions. They protect the soil and seed from water and wind erosion, reduce evaporation from the soil surface, increase the humidity of the soil, moderate temperature fluctuations at the soil surface, and dissipate the energy of falling water droplets to decrease disturbance of the soil surface.
There are many types of mulch available. Straw and hay are somewhat effective, but contaminate the seed bed with weed seeds. Hydro-mulch requires mixing and spray application equipment. Pelletized mulches are weed-free, and can be applied with standard rotary or drop spreaders. However, such mulches are fairly dense. Because of the density, it would be necessary to apply these mulches at an extremely high rate in pounds per area in order to cover a substantial amount of the seed bed area. Consequently, mulch pellets are applied to cover only a portion of the seed bed. As a result, they are not as effective as other mulches in protecting the underlying seed bed.